Tails - Privacy LiveDVD/USB 3.71

Tails is a live DVD or live USB that aims at preserving your privacy and anonymity.

It is a complete operating-system designed to be used from a DVD or a USB stick independently of the computer's original operating system. It is Free Software and based on Debian GNU/Linux.
It helps you to:

use the Internet anonymously almost anywhere you go and on any computer:
all connections to the Internet are forced to go through the Tor network;

leave no trace on the computer you're using unless you ask it explicitly;